Re: selftests/x86/fsgsbase_64 test problem

[H. Peter Anvin]

On 01/29/18 10:26, Andy Lutomirski wrote:
>>>
>>> That will utterly suck on non-UMIP machines that have
>>> hypervisor-provided UMIP emulation.
>>
>> Is that a valid thing to optimize for, especially given that paranoid
>> entries aren't the most common anyway?
> 
> A bunch of people seem to care about NMI performance for perf.
>

That wasn't really the question...

> And the current patch set works without this trick.

But I believe the tricks it uses are fragile.

> FWIW, if we switch all entries to the entry text trampoline, we get direct percpu access for free.

That might be a better option.

	-hpa